1. Statement of the Technical Field
The present invention relates to the field of radomes, and more particularly to low loss broadband radomes.
2. Description of the Related Art
Radomes are dome-like shells that are substantially transparent to radio frequency radiation. Functionally, radomes can be used to protect enclosed electromagnetic devices, such as antennas, from environmental conditions such as wind, solar loading, ice, and snow. Conventional radome types include sandwich, space frame, solid laminate, and air supported.
Radome induced wave perturbations are a principal consideration in radome construction. An ideal radome is electromagnetically transparent to a large number of radio frequencies, through a wide range of incident angles. However, in practice, conventional radomes are inherently lossy and are narrowbanded. Moreover, loss generally increases with angle of incidence. Traditionally, the radio frequency loss in radomes is minimized by adjusting the physical and electrical characteristics of the radome at the time of manufacture to achieve desired performance characteristics. For example, conventional radomes are often formed from a dielectric material having a thickness of a multiple of quarter a wavelength at a selected frequency. When so formed, a very small reflection coefficient will result at that frequency. Unfortunately, such a radome transmits electromagnetic waves with minimal loss only over a narrow frequency band about the selected frequency.
In order to overcome this limitation, some radomes are made of several layers, so that a broader group of frequencies can be transmitted with low loss. These multilayered radomes, still only have performance characteristics resulting in low reflections over a small set of pre-established frequencies and incident angles.
Accordingly, conventional radomes have a set of performance characteristics that are fixed at the time of their manufacture. The performance characteristics cannot be dynamically altered or modified as operational conditions change. The operational conditions can change based on any number of criteria such as technological upgrades, standard changes, and/or redistribution of portions of the electromagnetic spectrum.